Git Kata 4: Merge Conflicts

Step 1: Modify the file in the main branch#

To append to the file and save:

• Add (I want ripple chips) to Crispy Chips.
  • Crispy Chips (I want ripple chips)
  • Save the changes.

This step adds a new comment to the Crispy Chips line.

The command to commit the change to the repository is given below.

The output will be something like this:

This step commits the change made to the Crispy Chips line.

The output of the command is:

Step 2: Modify the file innewbranch#

The command to switch to newbranch is given below.

When we execute the command above, the output will be something like this:

This command switches to newbranch.

To append in the file and save:

• Switch to the text editor and reload the file.
• Add (I’ll take barbecue) to Crispy Chips:
  • Crispy Chips (I’ll take barbecue)

This step makes a conflicting change in newbranch to the same Crispy Chips line we modified in the first step. There are now conflicting versions of the same line of the same file between main and newbranch.

The command to commit the change to the repository is given below.

The result will be something like this:

This step commits the change made in newbranch to the Crispy Chips line of storelist.txt.

The command to switch to main is given below.

The result will be something like this:

This step switches the current branch back to main.

The command to display the difference between the branches is given below.

After running the command above, the output will be something like this:

Once again, git diff displays the differences between main and newbranch. The storelist.txt file has been modified again, and we see the current differences in the versions between branches.

This output displays two separate difference hunks: the Yummy Yogurt line is still different in the newbranch version, while the other hunk shows the difference we just created in the Crispy Chips line.

The output includes:

Step 3: Merge and resolve conflicts#

The command to switch to newbranch is given below.

The output will be something like this:

The Git merge command attempts to merge newbranch and main. This execution is different from the last git merge in the previous step because the Crispy Chips line has conflicting changes in both branches. Git cannot auto-merge, so the output indicates that there’s a merge conflict.

Reload the file by switching to the text editor and reloading storelist.txt.

The first step in resolving a merge conflict is to review the conflict headers added by Git to the file. Git annotates the file with markers indicating the version of the Crispy Chips line in main (indicated by HEAD, because main is the current branch) and newbranch.

The conflict headers are formatted as follows:

We remove the conflict headers and combine the comments: Crispy Chips (Ripple chips and barbecue).

The merge conflict is resolved by editing the line with the conflict (a single line in this example, but can be multiple lines). This situation calls for a compromise—the coders will be buying both Ripple and barbecue chips.

The command to commit the change to the repository is given below.

After the execution of the command above, the output will be something like this:

The git merge operation in the previous step didn’t create a new commit because the merge conflict had to be resolved first. Git marked the file with conflict headers to assist us with making the desired changes. We had to take it from there and edit the file by hand. Once the desired changes were made, they could be committed.

The previous Git merge command didn’t create a commit; however, it did create a pending merge. This Git commit then creates a new merge commit.

The command to display the repository log in graph format is given below:

The output will be something like this:

The git log command is used to view the commit history of a repository.

The --graph and --pretty=oneline options display the history in a vertical graph format, similar to the horizontal graphs we’ve been using to visualize the commit history and branching. If we flip this vertical graph, we can see that it has essentially the same shape as our horizontal visualization:

Vertical graph representations are commonly used in graphical Git tools to display long histories.

Practice commands#

We’ve given a terminal and a table containing a list of commands discussed in this lesson. Try out these commands after running the terminal, and check out the results!